Abstract
AbstractRock glaciers are receiving increased attention as a potential source of water and indicator of climate change in periglacial landscapes. They consist of an ice‐debris mixture, which creeps downslope. Although rock glaciers are a wide‐spread feature on the Tibetan Plateau, characteristics such as its ice fraction are unknown as a superficial debris layer inhibits remote assessments. We investigate one rock glacier in the semiarid western Nyainqêntanglha range (WNR) with a multi‐method approach, which combines geophysical, geological and geomorphological field investigations with remote sensing techniques. Long‐term kinematics of the rock glacier are detected by 4‐year InSAR time series analysis. The ice content and the active layer are examined by electrical resistivity tomography, ground penetrating radar, and environmental seismology. Short‐term activity (11‐days) is captured by a seismic network. Clast analysis shows a sorting of the rock glacier's debris. The rock glacier has three zones, which are defined by the following characteristics: (a) Two predominant lithology types are preserved separately in the superficial debris patterns, (b) heterogeneous kinematics and seismic activity, and (c) distinct ice fractions. Conceptually, the studied rock glacier is discussed as an endmember of the glacier—debris‐covered glacier—rock glacier continuum. This, in turn, can be linked to its location on the semiarid lee‐side of the mountain range against the Indian summer monsoon. Geologically preconditioned and glacially overprinted, the studied rock glacier is suggested to be a recurring example for similar rock glaciers in the WNR. This study highlights how geology, topography and climate influence rock glacier characteristics and development.
Highlights
In the context of climate change, glacial and periglacial landscapes are receiving increased attention as a water resource, especially in semiarid climates with growing population, for example, the Tibetan Plateau (Bolch et al, 2019; Hock et al, 2019; Immerzeel et al, 2020; Sun et al, 2018)
The analysis focused on three objectives: (a) determining the active layer thickness by passive seismic noise analysis, (b) detecting and locating seismic signals due to cracks emerging from the landform under investigation, and (c) by complementing Interferometric Synthetic Aperture Radar (InSAR)'s low sensitivity toward northward and southward displacement
We suggest to use a non-genetic term, which is based on the typical substrate components of a rock glacier.The classification allows an interpretation as glacial ice remnants with a recent periglacial characteristic like a typical active layer with a homogeneous thickness
Summary
In the context of climate change, glacial and periglacial landscapes are receiving increased attention as a water resource, especially in semiarid climates with growing population, for example, the Tibetan Plateau (Bolch et al, 2019; Hock et al, 2019; Immerzeel et al, 2020; Sun et al, 2018). Glacial and periglacial landforms are sensitive to climate warming and represent significant water reservoirs in semiarid environments and lowlands BUCKEL ET AL. Visible features include rock glaciers, which are primarily comprised of angular-rock debris and interstitial ice, ice lenses, and a coarse outer debris layer, which freezes and thaws seasonally. This so-called active layer provides insulating and damping properties against atmospheric influences (Barsch, 1996; Haeberli et al, 2006) and suggests that rock glaciers are climatically more resistant than debris-free and debris-covered glaciers (Jones et al, 2021). Rock glaciers are expected to have a long-term importance for water supply under the current global warming trend (Halla et al, 2021; Jones, Harrison, Anderson, & Whalley, 2019; Juliussen & Humlum, 2008; Millar et al, 2013)
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